package jiekou2;

import java.io.InputStream;

public class Test {
    public static void main(String[] args) {


        D d= new D();

      boolean isOk=  d instanceof A;
        System.out.println(isOk);

        isOk=  d instanceof B;
        System.out.println(isOk);


        isOk=  d instanceof C;
        System.out.println(isOk);

    }
}
